Safety device for fluid operated machines
OwnerMurray Andrew Hodgesinventor
Life of this patent
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Abstract
The supply of operating air or oil to a press, shears or like machine is controlled by a pair of spool valves connected in series and each operates a pair of switches. The switches connect DC current to the solenoids via external relays which open and close the valves. The external relays are standard components on the switchboard of the machine subject to control. Sharing the control between two valves allows malfunction in either valve to indicate the system needs correction while at the same time preventing supply to the machine. The switches are coupled to the DC switchboard of the machine by cables and thus can be retrofitted.
Claims12
Safety apparatus for controlling the supply of pressure fluid to the machine, comprising two valves connectable in series capable of controlling the admission of pressure fluid to the machine in response to a START signal and means to detect a malfunction in either valve, whereby supply in response to a further START signal is prevented.
A kit of parts comprising a pair of spool valve assemblies each with an associated solenoid, a double limit switch and a cable capable of connecting the switch conductors to the conductors of other machine to be controlled.
A spool valve assembly substantially as herein described.
Dependencies are inferred from the claim text.